This antiquated term is sometimes used by blood bankers with a bit more “experience.” The word itself roughly means “of the same species.” To blood bankers that use it, however, it means exactly the same as “allogeneic“; that is, it refers to blood from a different person. The problem is that the word really sounds like “autologous“, so many students confuse the two phrases and think “homologous” means blood from the same person.